Flying leads are commonly used in the offshore oil and gas industry to connect two pieces of equipment located subsea. Flying leads may be hydraulic, electro-hydraulic, loose tube or jacketed. The flying leads shown in this patent application are jacketed. A flying lead is an elongate bundle of tubes and/or cables with a first cobra head assembly on one end of the elongate bundle and a second cobra head assembly on the other end of the elongate bundle, as is well known to those skilled in the art.
Several different companies produce flying leads and there are several different designs for the cobra heads. For example the cobra heads shown in FIGS. 1-20 are designed by FMC Corporation. These FMC cobra heads use separate buoyancy modules during subsea installation. Applicant makes no claim the design of the FMC cobra head. Deep Down, Inc., the assignee of this application, produces Moray® brand flying leads; some of which have an integral buoyancy module on each cobra head as shown in FIGS. 21-27.
There are at least two methods for deploying flying leads. The first method is over a lay chute from the stern of a ship. The second method is using a subsea deployment system. In the past, different types of apparatus were needed to practice each method.
A. First Method. Deep Down and others have used the first method for years to deploy flying leads. Most contractors use a vertical drive unit with a removable carousel when deploying flying leads over the stern mounted lay chute. These vertical drive units are well known to those skilled in the art. Deep Down developed a horizontal drive unit for use with a rapid deployment cartridge and a lay chute.
Using either a vertical or a horizontal drive unit, the flying lead goes over a stern mounted lay chute and is installed with the assistance of a ROV. A down line from the ship lowers the flying lead to the seafloor. Worldwide this stern mounted lay system is probably the most common way to install flying leads and is well known to those skilled in the art. The Deep Down rapid deployment cartridge was only compatible with the Deep Down horizontal drive unit; the rapid deployment cartridge was not compatible with any mud mat.
B. Second Method. Deep Down developed another type of subsea deployment system in approximately 2006 for installation of flying leads. This system used a custom designed cartridge that was not compatible with a horizontal drive unit. The flying lead was wound on the custom cartridge. This custom cartridge engaged a mud mat which was lowered over the side of the ship. Once on the seafloor, the flying lead was installed by a remote operated vehicle (ROV) with the assistance of a down line from the ship. There is a need for a universal system that can use either the first method or the second method, depending on the customer's requirements. There is a need for a universal apparatus that can deploy both flying leads with integral buoyancy and flying leads that have a separate buoyancy module.